Figure 1.

Effects of inhibition of either complexes I and IV or the AOX on respiration and physiology under normal and stress conditions. A, Respiration capacities were compared between mitochondria isolated from Arabidopsis plants lacking either complexes I and IV (rpoTmp mutants) or the AOX (aox1a mutants) and wild-type plants. Rates of TCA cycle-driven respiration were determined for all mutant lines and the wild type (i and iii). The electron transport capacities of the AOX and the cytochrome oxidase in mitochondrial membranes from rpoTmp and aox1a, respectively, were measured in the presence of AOX- or complex IV-specific substrates and compared with wild-type rates (ii and iv). *, Significant differences. B, In vivo KCN-resistant respiratory rates expressed as a percentage of total respiration in leaf discs under normal growth and MLD (ML+D) conditions. Error bars indicate SE. *, Significant differences. C, Physiological response of Arabidopsis plants to MLD treatment showing increased anthocyanin pigment accumulation after 4 d of treatment in both rpoTmp and aox1a lines compared with wild-type (Col-0) plants. Plants were grown in normal conditions for approximately 4 (Col-0; aox1a) or 5 weeks (rpoTmp) to reach a comparable developmental stage before being transferred to MLD. The aox1a plant images were taken from Giraud et al. (2008).